One of the first tests of General Relativity has been the deflection of light by the Sun, which has been first measured in 1919 during a total solar eclipse, finding an agreement with the theoretical predictions. Since then a lot of measurements of such effect have been done, using radio telescopes to observe thousands of radio galaxies and quasars over the entire celestial physics. Moreover, a related phenomenon known as gravitational lensing, is nowadays a standard astrophysical tool used to study the distribution of dark matter in the universe and for imaging the most distance galaxies. Nowadays, there is also the Event Horizon Telescope which uses the light bending phenomenon to study supermassive black holes [1]} [2]}.
